35 research outputs found

    Interoperability of GPON and WiMAX for network capacity enhancement and resilience

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    This paper was published in Journal of Optical Networking and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/JON/Issue.cfm. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law. Copyright Optical Society of America.The interoperability of standard WiMAX and GPON is shown to overcome the wireless spectrum congestion and provide resilience for GPON through the use of overlapping radio cells. The application of centralised control in the optical line terminal (OLT) and time division multiplexing for upstream transmission enables efficient dynamic bandwidth allocation for wireless users on a single wavelength as well as minimised optical beat interference at the optical receiver. The viability of bidirectional transmission of multiple un-coded IEEE802.16d channels by means of a single radio frequency (RF) subcarrier at transmission rates of 50 Mbits/s and 15 Mbits/s downstream and upstream respectively for distances of up to 21 km of integrated GPON and WiMAX micro-cell links is demonstrated.Peer reviewe

    Electrical source of surface plasmon polaritons based on hybrid Au-GaAs QW structures

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    In this paper, the electrical excitation of surface plasmon polaritons (SPPs) based on a hybrid metal-semiconductor quantum well (QW) structure is investigated by finite-difference time-domain The hybrid structure could serve as a plasmonic source for integrated plasmonic circuits

    Hierarchical Honeycomb-structured Electret/Triboelectric Nanogenerator for Biomechanical and Morphing Wing Energy Harvesting

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    Flexible, compact, lightweight and sustainable power sources are indispensable for modern wearable and personal electronics and small-unmanned aerial vehicles (UAVs). Hierarchical honeycomb has the unique merits of compact mesostructures, excellent energy absorption properties and considerable weight to strength ratios. Herein, a honeycomb-inspired triboelectric nanogenerator (h-TENG) is proposed for biomechanical and UAV morphing wing energy harvesting based on contact triboelectrification wavy surface of cellular honeycomb structure. The wavy surface comprises a multilayered thin film structure (combining polyethylene terephthalate, silver nanowires and fluorinated ethylene propylene) fabricated through high-temperature thermoplastic molding and wafer-level bonding process. With superior synchronization of large amounts of energy generation units with honeycomb cells, the manufactured h-TENG prototype produces the maximum instantaneous open-circuit voltage, short-circuit current and output power of 1207 V, 68.5 μA and 12.4 mW, respectively, corresponding to a remarkable peak power density of 0.275 mW/cm3 (or 2.48 mW/g) under hand-pressing excitations. Attributed to the excellent elastic property of self-rebounding honeycomb structure, the flexible and transparent h-TENG can be easily pressed, bent, and integrated into shoes for real-time insole plantar pressure mapping. The lightweight and compact h-TENG is further installed into a morphing wing of small UAVs for efficiently converting the flapping energy of ailerons into electricity for the first time. This research demonstrates this new conceptualizing single h-TENG device's versatility and viability for broad-range real-world application scenarios

    Microwave Synthesis and High‐Mobility Charge Transport of Carbon‐Nanotube‐in‐Perovskite Single Crystals

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    Organolead trihalide perovskites have emerged as a new class of competitive solution-processed semiconductors due to their unique optoelectronic properties. However, poor ambient stability and charge transport are the Achilles’ heel of hybrid perovskites, thus limiting their applications. In this work, microwave-assisted synthesis is applied for the first time to rapidly grow perovskite single crystals embedded with single-wall carbon nanotubes. These nanotube-in-perovskite single crystals are endowed with a carrier mobility one order of magnitude higher than the pure counterpart and the related photodetectors show an ultrafast photo-response speed (5 and 80 ns for rise and decay time, respectively). The fast and uniform heating of microwave irradiation facilitates the synthesis of ambient-stable crystals with nanoscale additives, paving the way to creating a wide range of mixed-dimensional perovskite-based nanocomposites with optimal properties and device performance

    Shortened Telomere Length Is Associated with Increased Risk of Cancer: A Meta-Analysis

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    BACKGROUND: Telomeres play a key role in the maintenance of chromosome integrity and stability, and telomere shortening is involved in initiation and progression of malignancies. A series of epidemiological studies have examined the association between shortened telomeres and risk of cancers, but the findings remain conflicting. METHODS: A dataset composed of 11,255 cases and 13,101 controls from 21 publications was included in a meta-analysis to evaluate the association between overall cancer risk or cancer-specific risk and the relative telomere length. Heterogeneity among studies and their publication bias were further assessed by the χ(2)-based Q statistic test and Egger's test, respectively. RESULTS: The results showed that shorter telomeres were significantly associated with cancer risk (OR = 1.35, 95% CI = 1.14-1.60), compared with longer telomeres. In the stratified analysis by tumor type, the association remained significant in subgroups of bladder cancer (OR = 1.84, 95% CI = 1.38-2.44), lung cancer (OR = 2.39, 95% CI = 1.18-4.88), smoking-related cancers (OR = 2.25, 95% CI = 1.83-2.78), cancers in the digestive system (OR = 1.69, 95% CI = 1.53-1.87) and the urogenital system (OR = 1.73, 95% CI = 1.12-2.67). Furthermore, the results also indicated that the association between the relative telomere length and overall cancer risk was statistically significant in studies of Caucasian subjects, Asian subjects, retrospective designs, hospital-based controls and smaller sample sizes. Funnel plot and Egger's test suggested that there was no publication bias in the current meta-analysis (P = 0.532). CONCLUSIONS: The results of this meta-analysis suggest that the presence of shortened telomeres may be a marker for susceptibility to human cancer, but single larger, well-design prospective studies are warranted to confirm these findings

    Advances in Heterogeneous Catalysts for Lignin Hydrogenolysis

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    Abstract Lignin is the main component of lignocellulose and the largest source of aromatic substances on the earth. Biofuel and bio‐chemicals derived from lignin can reduce the use of petroleum products. Current advances in lignin catalysis conversion have facilitated many of progress, but understanding the principles of catalyst design is critical to moving the field forward. In this review, the factors affecting the catalysts (including the type of active metal, metal particle size, acidity, pore size, the nature of the oxide supports, and the synergistic effect of the metals) are systematically reviewed based on the three most commonly used supports (carbon, oxides, and zeolites) in lignin hydrogenolysis. The catalytic performance (selectivity and yield of products) is evaluated, and the emerging catalytic mechanisms are introduced to better understand the catalyst design guidelines. Finally, based on the progress of existing studies, future directions for catalyst design in the field of lignin depolymerization are proposed

    Competition of Dual Roles of Ionic Liquids during In Situ Transesterification of Wet Algae

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    Ionic liquid (IL)-catalyzed in situ transesterification (IST) of wet algae is a promising strategy for energy-efficient biodiesel production owing to the dual roles of ILs as both solvents of the cell wall and catalysts of transesterification, while their variations and interactions within different water contents, which subsequently affect biodiesel production, are still out of knowledge. Accordingly, the variations of fatty acid methyl ester (FAME) yields and cellulose solubilities of [Bmim][HSO4], [Bmim]- [H2PO4], and [Bmim]2[HPO4] under different water conditions are experimentally and theoretically studied. Results indicate that [Bmim][HSO4], [Bmim][H2PO4], and [Bmim]2[HPO4] are acid, weak alkaline, and strong alkaline catalysts of transesterification of lipid with methanol, respectively. FAME yields of both [Bmim]- [HSO4]- and [Bmim][H2PO4]-catalyzed reactions increase initially with the addition of 1.5 g of water, while they decrease with the increase of water content because of the consequent decline of the nucleophilic index and electrophilic index of the OH groups of [Bmim][HSO4] and [Bmim][H2PO4], respectively. Analogously, slight decreases of FAME yields of [Bmim]2[HPO4]-catalyzed transesterification are observed within 0.0−3.0 g of water, while a notable decrease is presented when 6.0 g of water is added. Contrary to the variation of catalytic properties, the cellulose solubilities of [Bmim][HSO4], [Bmim][H2PO4], and [Bmim]2[HPO4] all decrease with the addition of 1.5 g of water, as the water molecules occupy the H-bonding sites of [Bmim][HSO4]−cellobiose (clb), while the H-bonding interactions of water−clb and water− [Bmim][H2PO4] formed by shared oxygen atoms are enhanced with the increase of water content, subsequently enhancing the Hbonding interactions of ILs−clb and relative cellulose solubilities. The variations of cellulose solubilities of ILs with the addition of 0.0−6.0 g of water are opposite to those of their catalytic properties. This study indicates that the cellulose solubilities and catalytic properties of [Bmim][HSO4], [Bmim][H2PO4], and [Bmim]2[HPO4] compete with each other under different water conditions, providing a potential strategy to offset the negative effect of water content on IST of wet algae

    Sexual violence against women remains problematic and highly prevalent around the world

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    Abstract Background Sexual violence is far more prevalent in most societies than is usually suspected in daily life. However, no study has systematically summarized the global prevalence rate and the major outcomes of sexual violence against women. Methods We directed a wide-raging search in the PubMed, Embase, and Web of Science, catalogs since the beginning to December 2022 for relevant reports about the incidence of sexual fighting touching females. The occurrence frequency was assessed with a random-effects model. The heterogeneity was estimated with I 2 values. Differences by research features were assessed over subgroup evaluation and meta-regression. Results A total of 32 cross-sectional studies were included (a total of 19,125 participants). The pooled sexual violence rate was 0.29 (95% CI = 0.25–0.34). Subgroup analyses found that there was a higher rate of sexual violence against women in 2010–2019 period (0.33, 95% CI = 0.27–0.37), developing countries (0.32, 95% CI = 0.28–0.37), and interview (0.39, 95% CI = 0.29–0.49). The analysis found that more than half of women (0.56, 95% CI = 0.37–0.75) had post-traumatic stress disorder (PTSD) after experiencing sexual violence, and only a third of women considered seeking support (0.34, 95% CI = 0.13–0.55). Conclusions Nearly one out of every three (29%) women around the world has been a victim of sexual violence in their life. This current study investigated the status and characteristics of sexual violence against women, which could provide an important reference for police and emergency health services management
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